FIG. 8 shows various ladder rung attachment methods in the prior art. Rungs 2 are attached to a ladder rail 1 forming protrusions on the outer, otherwise smooth, surface of the ladder rail. The attachments may include a rung-end flange 3 or a plate 4 or rivets 5. If one adheres a shoulder pad to the outside of the rail and the pad is sufficiently resilient to be effective to cushion the weight of the ladder on a shoulder, the protrusions tend to push the pad away from the rail, placing the adhesive in tension with crack propagation beside the protrusion. Most adhesives cannot withstand such constant tensile force with crack propagation and will fail over time.
There have been various types of shoulder pad and shoulder cushion inventions for ladder rails in the past. Most were a type that allowed the shoulder pad to be attached and then detached, with various types of connectors, clips or hook and loop (Velcro) devices. Others that were attached with adhesives were short enough to fit between rungs (typically about 8 inches, possibly up to 10½ inches) so that the adhesion would not be compromised by the pad extending over a protrusion such as a rung end. Extending the pad to longer than 12 inches, the typical center-to-center distance between rungs, makes a more effective and useful pad.